266 THE RIDDLE OF LIFE presents thousands of instances in which the animal's building of its bodily structures or appendages and its building of external structures with foreign material, go on in most intimate co-operation as complementary parts of one process ; and the outer building, being what we call instinctive activity, presents all the essentials of a mental or psychical activity; while the same essential marks are presented, though more obscurely, by the morphogenetic processes which build the body and its organs; namely, in both cases the activities are teleo- logical (obstinately persisting towards the specific goal), are intelligently adaptive in high degree (reverting to and restoring normality after disturbances), and yet in both cases they are mnemic, striving to repeat, to reproduce the pattern common to the species, the pattern impressed upon it by countless repetitions of essentially the same course of activity. I have in mind more particularly such activities as the building of cocoons or other cells for the harbouring of the creature. The two kinds of construction often go on in strictly supplementary fashion, each implying and requiring the other. And in many such cases it is clear that the bodily movements or behaviour and the growth processes are alike partial responses of the whole organism to the same impressions or environmental influence; as when a fall of temperature provokes both a growth of hair and retreat to some sheltered spot. Dr, E. S. Russell, who has insisted on the essential similarity of the two kinds of response, proposes the adjective 4 morphoplastic' for the growth processes responsive to outer influences. He remarks : ' The line between behaviour-response and morphoplastic is hard to draw.' And he points out that normally behaviour- response involves some degree of morphoplastic-response,